Cyclodextrin; hereinafter refered to as "CD", is a nonreducing malto-oligosaccharide where 6 to 12 glucoses are bonded together in a cyclic form via glucoside bonding. For industrial CD production, .alpha.-CD with six glucoses bonded together, .beta.-CD with seven glucoses bonded together, and .gamma.-CD with eight glucoses bonded together, are produced as a single product or a mixture thereof.
CD, an amphoteric substance having the hydrophilic outer ring circumference and also having the hydrophobic pore, has an inclusion function to stably include a variety of molecules and the like in the hydrophobic pore.
Therefore, CD potentially prepares volatile matters into non-volatile matters or provides masking of unpleasant odor, so CD is applicable in a wide variety of fields, for example, for use in medicinal products, foodstuffs, cosmetics and the like.
CD has conventionally been produced via an enzyme reaction, ie. the reaction of a CD generating enzyme (cyclodextrin glucanotransferase; hereinafter referred to as "CGTase") with starch as a substrate. The substrate concentration should preferably be higher from industrial point, which involves the increase in the viscosity of the reaction solution whereby the stirring procedure gets hard along with a lower reaction rate. Thus, a method has been proposed, comprising prelimlnarily subjecting starch to the pretreatment process with .alpha.-amylase for liquidation to decrease the viscosity, but the process is complex.
Because the reaction product is produced as a mixture of CDs of .alpha., .beta., and .gamma. type, purification is needed so as to obtain .beta.-CD for primary use, and thus, the decrease of the yield is unavoidable. Alternatively, no report has been issued of the CD production via CGTase using a substrate other than starch.
The present invention has been undertaken from such respect. The objective of tile present invention is to provide a method of producing .beta.-CD with a substrate other than starch at a higher efficiency.